A veteran gets his day this Wednesday on Criminal Minds (CBS, 9/8c), when the BAU’s investigation into homeless people murdered at the Santa Monica Pier unexpectedly reunites Rossi with his Marine sergeant from Vietnam. Joe Mantegna — who this past weekend cohosted PBS’ inaugural National Salute to Veterans special — shared with TVLine a preview of the illuminating hour, promising that guest star Meshach Taylor (Designing Women) will blow you away in an atypically dramatic turn.

TVLINE | It sounds like you have an especially resonant episode this week, and not just the usual unsub grisliness.
Well, it’s kind of a dual story because we have this unsub who’s out doing his usual kind of mayhem, preying on the homeless, but the secondary story comes in when, during our investigation on Los Angeles’ Skid Row, I spot a guy that turns out to be my commanding officer when I served in Vietnam, 40-plus years ago.

TVLINE | I have to imagine Rossi is pretty surprised by that.
He is very surprised, and what’s interesting, too, is they incorporate flashbacks, so all of a sudden it goes to black-and-white and there we are in Vietnam with a 19-year-old version of me (played by Robert Dunne) as well as the younger version of Meshack Taylor (Joseph H. Johnson Jr.). It’s an idea that I’ve been kicking around for a long time, and my assistant wrote a wonderful storyline that they were able to incorporate as part the episode. I’m just a strong believer that with a show that’s as successful and long-running as ours, the fan base becomes invested in the characters as much as they are in the stories. We’re always going to have an unsub, we’re always going to have a crime — that’s the nature of the show — but at this point they really like to look behind the curtain and see what’s going on in the lives of the characters, and this gives them a chance to not only get into the background of David Rossi but also for me to be able to tap into something that I feel very passionate about, which is our United States military and some of the problems that the veterans face.

TVLINE | How do the flashbacks inform the current day story and Rossi’s unexpected reunion with his sergeant?
The flashbacks show the genesis of both that relationship and my character, that I was a very different kind of human being at 19 than what I am today. It also shows what happens under a very trying situation and how it impacted not just myself but also my officer. And then it makes a statement of how things like that can impact our military in general. There is a problem of homelessness among the U.S. military, and the fact that we’re able to actually incorporate something like this group called New Directions, which tries to help homeless veterans, is a great and positive thing.

TVLINE | Yeah, these veterans come back broken in any number of ways. I imagine a good chunk of them just have trouble getting back on their feet and rediscovering who they are.
Of course. I mean, we do have facilities like the VA and all that, but those only can do so much. For the most part they really do need additional help but they also need our support, for even the average citizen just to be aware. For the last 10 years we’ve been in a conflict, and we literally send hundreds of thousands of men and women over there. Not all of them are going to come back 100 percent.

TVLINE | Meshach Taylor is obviously best known for playing a rather flamboyant character on Designing Women. How did he do with this dramatic material?
If he doesn’t get an Emmy nomination, my feeling is, “Why bother to give them out?” He was always part of this in my mind because this is a guy that I’ve known for literally over 40 years. He’s certainly one of my oldest friends in the world, I’m the godfather of his son, he’s the godfather of one of my daughters…. And I’ve known him as a brilliant stage actor in Chicago working at a theater company with Dennis Franz (NYPD Blue) and myself, so I always knew that there was so much more to him. It’s not that another actor couldn’t do it, but I always knew he would be a tremendous choice and that it would shock people who had, let’s say, a stereotypical image of how they think Meshach Taylor is going to come across. I think people are going to be freaked out when they see him and realize, “Geez, what an actor this guy is!” They’ll see him in a whole different light. It’s like if you had seen Denzel Washington doing [St. Elsewhere in the 1980s], back then you might not have thought he was going to do much more, either.